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What is lactose intolerance?

Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products.

What are the symptoms of lactose intolerance?

If you experience symptoms such as wind, diarrhoea, bloating and stomach cramps a few hours after  consuming food or drink that contains lactose, you may be intolerant to lactose.

When you need to see your GP

Lactose intolerance can be similar to several other conditions, such as irritable bowel syndrome (IBS), so it's important to see your GP for a diagnosis before removing milk and dairy products from your diet. Milk and dairy products are an important source of calcium for most people.

If your GP suspects you have lactose intolerance, you may be advised to avoid foods and drinks containing lactose for two weeks to see if your symptoms improve. If they do you will be advised to limit the amount of lactose you consume and substitute cow’s milk for a lactose free milk, or plant milk, such as Provitamil Oat Drink.

What causes lactose intolerance?

The body digests lactose using an enzyme called lactase to break down lactose into two sugars called glucose and galactose, which can be absorbed into the bloodstream.

People with lactose intolerance don't produce enough lactase, so lactose stays in the digestive system where it is fermented by bacteria, leading to the symptoms associated with lactose intolerance.

There are different causes of lactose intolerance. Sometimes it is a temporary condition associated with other illnesses, such as undiagnosed celiac disease, but it is more usual for it to be permanent. Most cases of lactose intolerance develop in adults and are inherited, but cases in young children are often caused by an infection in the digestive system and may only last for a few weeks.

Food allergy or intolerance?

Lactose intolerance should not be confused with a milk or dairy allergy. Food allergies are caused by an immune reaction to a food and cause symptoms such as a rash, wheezing and itching.

Allergic reactions can be triggered by even a tiny particle while most people with lactose intolerance can still consume foods containing small amounts of lactose without experiencing any problems (although this varies from person to person).

What is the treatment for lactose intolerance?

There is no cure for lactose intolerance, but limiting the intake of milk and dairy food will usually help manage symptoms.

A carefully managed lactose free diet should be able to supply the body’s need for calcium and vitamin D, however some people may require supplements.  Your GP may refer you to a dietitian for further advice.

In addition to dietary changes, lactase substitutes may also be helpful. These are drops or tablets you can take with your meals or drinks to improve your digestion of lactose.

Who becomes lactose intolerant?

Rates of lactose intolerance vary between different ethnic groups. In northern Europe about one in 50 people have some degree of lactose intolerance, compared to most people of Chinese descent.

This may be because people from places where there has historically been no ready access to milk, such as Africa or East Asia, may not have evolved the ability to digest lactose as there was no significant benefit in being able to do so.

In the UK, lactose intolerance is more common in people of Asian or African-Caribbean descent.

Lactose intolerance can develop at any age. Most cases first develop in people from 20 to 40, although babies and young children can be affected.